Gypsum compositions capable of setting at elevated temperatures



M5. CQtiPOSlTlONS, txam COATING OR PLASTlC :2

. Patented Feb. 18, 1947 GYPSUM COMPOSITIONS CAPABLE OF SET- TING ATELEVATED TEMPERATURES William A. Whittier, Glenview, Ill., assignor toUnited States Gypsum Company, Chicago, 111., a corporation of IllinoisNo Drawing. Application September 21, 1944,

Serial No. 555.202

8 Claims. (01. 106-89) 2 The present invention relates to specialcalwith relatively small amount of certain cined gypsum compositionswhich contain ingrediate particularly those carbonates selected froments that enable them to set within a reasonable a? group consisting ofthe normal and basic car- Deriod of time even though they are maintaineda es of u 1 1 slum nicke n I s not at temperatures in excess of about130 F. 5 known just what e chem cal reaction might be It has long beendesirable to produce calcined and perhaps the effect is explainable onlyon the gypsum compositions which when gauged with basis of some form ofcatalysts. The empirical water will set in a reasonable time even thoughfact remains, however, as shown by a large numthe slurry resulting fromsuch admixture is mainber of tests, that the enumerated carbonates aretained at elevated temperatures, say from about capable of offsettingthe retarding eflect of heat 130 F. to about 175 to 190 F. Conditionsunder on a calcined gypsum slurry. which such temperatures may beencountered are It is of course well known that in setting, calin hotclimates, and particularly in the bottom cined gypsum. which is thecalcium sulfat hemiof deep wells where it has become customary tohydrate, CaSOrHzO, will unite with water to employ gypsum slurries forthe purpose of cereform ordinary y sum. namely the calcium sulmentingoil wells and the like. fate dihydrate, CaSO4.2H-zO.

Thus it has already been proposed in accord- This reaction can beaccelerated and retarded ance with the patents of Andrew 0. Hamilton, toa considerable extent. Thus the use of so Jr., Nos. 2.l91,652 and2,210,545, to cement ofl' oil called commercial retarders, which ingeneral are wells by introducing thereinto calcined gypsum 2oproteinaceous materials such for example as are compositions of suchcontrolled rates of setting produced from keratin by hydrolvsis andadmixthat the slurries will set at about the time that ture of theproduct with lime, will retard the set 5 the slurry reaches theformation in the earth of gypsum to a considerable-period, say up to 5where the break in the well has occurred. or 6 hours. On the other hand.the setting of a In some of these patents the accelerator is so slurryof calcined gypsum can be accelerated by balanced against the retarderthat a predetera number of materials, among the best of which minedsetting time can be relied upon. In anare seed crystals of calciumsulfate dihydrate other of these patents a retarded composition is whichmay be supplied to the mixture either in pumped into a well andaccelerator is then added the form of ground raw gypsum or formed in thein constantly increasing amounts until the setmixture by metathesis fromsuch substances as ting time has been so shortened or adjusted thataluminum sulfate and a calcium hydroxide-yieldthe slurry will set atabout the time it reaches ing alkaline reacting material such as lime orthe break in the well. Portland cement, etc. These seed crystals. by ac-Now it is a fact that the temperatures in rather celerating thematerial, more or less oflset the deep wells are higher than they are atthe surface 5 retarding effect of the retarder. By having both of theearth. It is well known that the further the materials present inbalanced amounts, the one penetrates into the earth, the higher are thegypsum is thereby more or less stabilized against temperaturesencountered, and in some of the changes in its setting rate, due toadventitious more modern and deep oil wells, temperatures as admixtures.However, its setting time will still high as 170 F. and sometimes evenhigher are 0 be influenced by a rise in temperature. not uncommon. It isself evident that if a gyp- The present invention, however, cures thatporsum composition is adversely eflfected as to its tion of the defectwhich lies in the lengthening 5 setting time as a result of getting intoa zone of of the setting time due to operating at high temsuch hightemperatures this will be a very undeperatures. Applicant has found thatby mixing sirable condition, as thus the setting will be subwith thecalcined gypsum relatively small stantially prevented. amounts of eitherthe normal or basic carbonates reo er, i has been kno for a l ti ofmagnesium; nickefbr'zinc, that he can render h t ypsum compositions areprevented from? themompositionpapable of settingjust about as setting byhigh temperature environment and in fast di-"atl'east reasonably fast,even though the fact advantage is taken of this retardation oftemperature t which t mixture is raised is L/ set by elevatedtemperatures in producing ypabove 130 F., and say up to 190 F. sumcastings. See for example the patent to Purely fo purposes ofexempliflcation, a num- Chassevant N 1, ber of examples will now begiven to illustrate ppli t has new discovered that e can the method ofapplying the present invention: stantially immunize calcined gypsumslurries against the retarding efi'ect of high temperatures, that is tosay, for example, within the range of from about to R, by incorporatingthere- ExAmrLn 1 This example describes two mixtures, the first ofwhich. is merely the prior art material, while the second is a materialcoming within the scope of the present invention.

Mixture N0. 1 is as follows:

Alpha gyps 2000 Portland Cement 10 Raw gyps 5 Rochelle sal 0.5

Mixture No. 2 is as follows:

Alpha gyps 2000 Portland ceme 10 Raw gyps 5 Rochelle sa 0.5 Basicmagnesium carbonate 0.75,

In the above mixtures alpha gypsum is a special high strength gypsummade in accordance with patent to Randell and Bailey No. 1,901,051.

Mixture N0. 1 and mixture No. 2 were tested under identical conditions,in each case gauging 100 parts by weight of the mixture with 45 parts byweight of water, and then pouring the mixture into a suitable vessel, inwhich the setting time could be accurately ascertained, and also inwhich certain temperatures could be accurately maintained. The resultswere as follows:

Setting time of Setting time 01 MW slurry at 76 F. slurry at 170 F.

Minutes M inuter It will be seen from the above test that the additionof magnesium carbonate to the composition shown actually evenaccelerated the setting time at 170 F., while the setting time of thecomposition containing no basic magnesium carbonate was retarded up to143 minutes, as against a set of 97 minutes at 76 F.

Similar results can be obtained by the use of normal or basic carbonatesof zinc and nickel.

Examples of these are given hereinbelow;

Exmu: 2

Two different base mixtures were employed, marked respectively basemixture No. 3 and base mixture No. 4, which were as follows:

Base mixture Base mixture #3 #4 Pounds calcined gypsum 2,000 2. 000Portland cement-.. 20 10 Gum m c 8 Commercial retarder l. 2

w gypsum l 5 Rochelle salt 0. 6 Additive 25 25 These mixtures were thentested at 70 F. and 150 F. with the results shown in Table I.

In the above mixture the commercial retarder was the ordinary well knownretarder material made from hydrolized keratin and line. The othermaterials are of course self-explanatory.

Particular attention is directed to the fact that as shown in Table I,the setting time of mixture 3 with basic magnesium carbonate was thesame at 150 F. as it was at 70 F. while with mixture 4, the setting timeat the higher temperature was actually less.

With nickelous carbonate with mixture 3, the difference was about 14minutes at the higher temperature, and the same with mixture 4.

Zinc carbonate, while effective, is not as good as the basic magnesiumcarbonate, the increase being roughly minutes at the higher temperature.Note, however, that where no additive was used, and the material wouldset as to mixture 3 in 69 minutes at 70 F., and as to mixture 4 in 62minutes at 70 F., there was no set at all at F., even at 420 minutes,that is to say 7 hours.

- In general it has been found that the effectiveness of the temperaturerange at which the material can be made to set runs up as high as E,which is not very far below the boiling point of water. In other words,when using the present invention, not much attention need be paid totemperature conditions. Thus, when operating in very hot regions of theearth, like in the Near East or in Southern Arabia, these mixtures wouldwork, while without the additive materials they would be quite useless.The same thing is true in working anywhere where by reason of the depthof the well the earth temperature lies within the ranges hereindescribed.

The methods of compounding the material are simple, and the carbonateadditive may be merely physically admixed with the gypsum and the otherset controlling ingredients. It is to be noted, however, that even whenno set controlling ingredients at all are employed, the stated type ofnormal or basic carbonates will still exert their effect of overcomingthe retarding efiect of heat.

As an obvious modification it may be mentioned that the addition of thenormal or basic carbonate may be accomplished by first mixing it withthe gauging water and then using the suspension of these carbonates togauge the gypsum cement composition. This is an advantageous way ofproceeding where shipments are made for use of the well sealing materialunder conditions where sometimes the temperatures are such that thecarbonate additives are not needed; therefore the operators can stir itinto the gauging water and thus get it into quite uniform mixture withthe slurry when needed.

As a still further alternative the additive may be admixed with thegypsum cement composition at the time the slurry is prepared, that is tosay, it may be sprinkled or poured into the slurry during the gaugingoperation.

In other words, it is to be emphasized that the manner of addition ofthe carbonate additive is a matter of no great concern.

As to the quantities, it has been found by experiment that from of 1% upto 5% based on the weight of the active setting material, that is tosay, the calcined gypsum, is the most effective range. Larger amountsmay of course be used, but do not add very much to the efiect, andnaturally are more expensive.

Ordinarily, compositions such as those shown in the mixtures numbered 2through 4, with the amounts of the additives as therein shown, are

Examiner to be considered as the preferred forms or the presentinvention, for which applicant claims:

1. A cementitious composition capable of setting at temperatures aboveabout 130 F. comprising as its major reactive ingredient over 90% byweight of calcium sulfate hemihydrate, and from about 0.25 to about byweight of a carbonate selected from the group consisting of the normaland basic carbonates of magnesium, nickel and zinc.

2. A calcined gypsum composition whose setting time is not much delayedby temperatures in excess of about 130 F. which comprises at least 90%by weight of calcined gypsum and from about 0.25% to about 5% of acarbonate selected from the group consisting of the normal and basiccarbonates of magnesium, nickel and; zinc.

3. Process of preventing the retardation of a calcined gypsum slurrywhose solids content comprises over 90% by weight of calcined gyp um bytemperatures of about 130 F. and higher which comprises incorporatingwith the gypsum slurry at any stage of its formation about 0.25% toabout 5%, on the basis of the weight of the calcined gypsum in saidslurry, of a carbonate selected from the group consisting of the normaland basic carbonates of magnesium, nickel and zinc.

4. A calcined gypsum composition suitable for cementing oil wells, andnot adversely afiected as to its setting time by temperatures aboveabout 130 F., comprising over 90% of calcined gypsum and from about0.25% to about 5.0% Of a carto 0.6 parts of Rochelle salts, and about 25parts of a. carbonate selected from the group consisting of the normaland basic carbonates of ma nesium, nickel and zinc.

6. Process of overcoming the retarding efl'ect of temperatures fromabout 130 F. to about 190 F. upon cementitious slurries whose solidscontent comprises over by weight of calcined gypsum which comprises theincorporation therewith at any stage of their production of smallamounts of basic magnesium carbonate.

7. Process of overcoming the retarding effect of temperatures from aboutF. to about F. upon cementitious slurries whose solids content comprisesover 90% by weight of calcined gypsum which comprises the incorporationtherewith at any stage of their production of small amounts of nickelouscarbonate.

8. Process of overcoming the retarding eflect of temperatures from about130 F. to about 190 F. upon cementitious slurries whose solids contentcomprises over 90% by weight of calcined gypsum which comprises theincorporation therewith at any stage of their production of smallamounts of basic zinc carbonate.

WILLIAM A. WHI'I'I'IER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS bonate selected from the group consisting of theNumber Name Date normal and basic carbonates of magnesium, 397,529Wooster Feb. 12, 1889 nickel and zinc, the remainder consisting of a 351,620,915 Parkhurst Mar. 15, 1927 mixture of set control reagents.1,901,054 Dailey Mar. 14, 1933 5. A calcined gypsum composition suitablefor 2,078,200 King Apr. 20, 1937 cementing oil wells and not adverselyaffected as 2,292,616 Dailey Aug. 11, 1942 to its setting time bytemperatures above about 130 R, which comprises a mixture of about 200040 FOREIGN PATENTS parts by weight of calcined gypsum, from about NumberCountry Date 10 to 20 parts of Portland cement, from about 5 2,467British 1905 to 10 parts of uncalcined gypsum, from about 0.0

Certificate of Correction :"1 P J '1 atent No 2,415,647: February 11,1941: 0

ROGER A. MACARTHUR ET AL.

It is hereby certified that error appears in the printed s eclfication fth numbered patent reqmrmg correction as follows: Column 3 line 13, fothe fait ehi. number 335,242 read 2,335,242; and that the said LettersPatent should be read with this correction therein that the the PatentOfiice. same may conform to the record of the case in Signed and sealedthis 22nd day of April, A. D. 1947.

LESLIE FRAZER, 7

First Assistant Oomz'ssz'oner of Patents.

Certificate of Correction Patent No: 2,416,035: February 18, 1947.

WILLIAM A. WHITTIER It is hereby certified that errors appear in theprinted specification of the above numbered patent requiring correctionas follows: Column 2, line 7, for catalysts read catalysis; column 3,line 72, Table 1, last column thereof, for 15 read 150; column 4, line3, for line read lime; and that the said Letters Patent should be readwith these corrections therein that the same may conform to the recordof the case In the Patent Office.

Signed and sealed this 22nd day of April, A. D. 1947.

LESLIE FRAZER,

First Assistant Qommz'ssz'oner of Patents.

